Grooves in the stool can be caused by diseases such as hemorrhoids and intestinal swellings. Under normal circumstances, the stool is smooth and long, stool with grooves means that the intestines or anus has a bulge, may be due to the following reasons: 1. Hemorrhoids: In hemorrhoids, the veins in the anal canal or lower rectum are engorged and enlarged, which may affect the shape of the stool. In addition to a groove in the stool, there may be anal pain, itching, blood in the stool and other symptoms. 2. Intestinal swelling: when there are intestinal polyps, tumors and other swellings, the stool in the process of passing through the intestinal tract will be squeezed because of the swelling, and the phenomenon of stool with grooves will occur. Therefore, once the phenomenon of grooves in the stool occurs, it is necessary to go to the hospital, complete the relevant examinations and carry out treatment under the guidance of the doctor.